3-27
HYDRAULIC SEALS
W A R N I N G
Do not check for hydraulic leaks with hands. If a mist of hydraulic oil is noticed
around a line or component, use cardboard or other material to check for location of
leak. High pressure fluid leaking from a small hole, can be almost invisible, yet have
enough force to penetrate the skin. If injured by escaping fluid, see a doctor at once.
Serious reaction or infection can occur.
All hydraulic fittings and hose connections should be kept tight to prevent loss of fluid from
the system and unnecessary dripping from the machine. Most hydraulic fittings on the
BMC RT-300 crane use o-ring seals, and if tightening the fitting fails to stop the leak, the o-
ring should be replaced.
Notes:
1. When installing an o-ring fitting with an adjustable nut and washer, be sure to back off
the nut, washer and o-ring as far as possible before threading the fitting into the port.
Then turn the fitting into the port as far as possible with fingers and turn it backward
until it is oriented properly. Torque the nut with a wrench, while holding the fitting with
a wrench.
2. Lubricate all seals before assembling.
3. Take care not to over tighten pipe threads on which Teflon sealer is used, particularly
in aluminum or castings.
Leaks in component parts such as pumps, valves, and motors that cannot be stopped by
tightening bolts can usually be stopped by replacing the seals in the component. Seal and
packing replacement is the only maintenance which owners should attempt on component
parts unless they have a well-equipped shop, with mechanics trained in hydraulic
component overhaul.
Leakage in the pump suction line may not cause oil to appear externally, but may allow air
to enter the line during operation. The air entrained in the oil will cause pumps to be noisy,
and if allowed to continue, can damage the pump. If a pump becomes noisy, immediately
check the fluid level in the reservoir and be sure all suction fittings are tight. If noise
continues, squirt hydraulic fluid on the suction connections, listen for a change in the noise
and watch for oil being sucked into a small opening in the connection. When the reservoir
is full, the shutoff valve is open and all suction connections are tight, most pump noises will
disappear. If they do not, a worn or faulty pump is indicated. On a routine basis, all hoses
should be checked for wear, deterioration, and physical damage. Defective hose should be
replaced for maximum economy for the user.
Courtesy of Crane.Market
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